Ultrastructural observation of human secondary yolk sac

1995 ◽  
Vol 53 ◽  
pp. 918-919
Author(s):  
D.A. Beckman ◽  
YP. Wang ◽  
G. Yang ◽  
M. Zeng ◽  
YP. Wang ◽  
...  
Keyword(s):  
Critical Period ◽  
High Capacity ◽  
Yolk Sac ◽  
Coelomic Fluid ◽  
Ultrastructural Observation ◽  
Standard Procedures ◽  
Developmental Age ◽  
Early Organogenesis ◽  
Endodermal Layer

The human secondary yolk sac persists for a short but critical period of development during early organogenesis. Although it is established that the yolk sac is the site of origin of several cell lines, a locus of hematopoiesis and secretes several proteins, the yolk sac may have other as yet less well defined functions. Here we focus on ultrastructural evidence of the role of the human yolk sac as an organ of exchange with the extraembryonic coelom and the yolk-sac cavity. Yolk sacs of 6 to 10 weeks developmental age were fixed and processed for light microscopy, TEM and SEM by standard procedures. Numerous microvilli, coated and uncoated vesicles, and lysosomes in the mesothelial layer together suggest a high capacity for pinocytosis of coelomic fluid and lysosomal digestion of internalized substrate. It is not known whether this process is a significant nutritional source for the yolk sac and embryo as it is in the rodent. Both SEM and TEM observations provide evidence of cilia on dispersed cells in the endodermal layer lining the yolk sac cavity. To our knowledge, there is only one other brief report of cilia on the human yolk sac.

scholarly journals Adolescence as a “critical period” in the heritage language use. Polish in Germany

2021 ◽  
Vol 7 (1) ◽  
pp. 301-315
Author(s):  
Hanna Pułaczewska
Keyword(s):  
Role Models ◽  
Personal Development ◽  
Critical Period ◽  
Growing Up ◽  
Age Related ◽  
The Media ◽  
Role Of Parents ◽  
Qualitative Part ◽  
The Impact

Abstract In the article, we consider the impact of adolescence upon the usage of Polish in Polish-German bilinguals raised and living in Germany and demonstrate how adolescence surfaces as a socially based “critical period” in this usage using results from a survey and interviews conducted with 30 teenagers. In the quantitative part of the study, we seek to establish whether adolescents’ age affected the pattern and quantity of their usage of Polish in the media and contacts with age peers, whether the latter two facets of growing up with Polish were interrelated, and which other factors affected peer-relevant activities in Polish. Both age and peer contact turned out to significantly affect the use of the media in Polish, while peer contact in Polish was affected by the parental use of Polish in parent-child communication. The qualitative part presents the context and motivation for using Polish by the youths in peer-relevant activities. We integrate the results with insights provided by child development psychology from the perspective of language socialisation theory and interpret the age-related decline of interest in the Polish media as an effect of a diminishing role of parents and the increasing role of age peers as role models in personal development.

scholarly journals Analysis of the genomic landscape of yolk sac tumors reveals mechanisms of evolution and chemoresistance

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Xuan Zong ◽  
Ying Zhang ◽  
Xinxin Peng ◽  
Dongyan Cao ◽  
Mei Yu ◽  
...  
Keyword(s):  
Copy Number Alteration ◽  
Germ Cell Tumors ◽  
Gonadal Development ◽  
Yolk Sac ◽  
Mutational Signatures ◽  
Whole Exome ◽  
Genomic Landscape ◽  
Yolk Sac Tumors ◽  
Molecular Aberrations

AbstractYolk sac tumors (YSTs) are a major histological subtype of malignant ovarian germ cell tumors with a relatively poor prognosis. The molecular basis of this disease has not been thoroughly characterized at the genomic level. Here we perform whole-exome and RNA sequencing on 41 clinical tumor samples from 30 YST patients, with distinct responses to cisplatin-based chemotherapy. We show that microsatellite instability status and mutational signatures are informative of chemoresistance. We identify somatic driver candidates, including significantly mutated genes KRAS and KIT and copy-number alteration drivers, including deleted ARID1A and PARK2, and amplified ZNF217, CDKN1B, and KRAS. YSTs have very infrequent TP53 mutations, whereas the tumors from patients with abnormal gonadal development contain both KRAS and TP53 mutations. We further reveal a role of OVOL2 overexpression in YST resistance to cisplatin. This study lays a critical foundation for understanding key molecular aberrations in YSTs and developing related therapeutic strategies.

scholarly journals Role of Radiotherapy in Recurrent Intra-Abdominal Yolk Sac Tumor

2021 ◽  
pp. 1010-1018
Author(s):  
Marhendra Satria Utama ◽  
Andi Kurniadi ◽  
A.A. Citra Yunda Prahastiwi ◽  
Antony A. Adibrata
Keyword(s):  
Case Reports ◽  
Yolk Sac ◽  
Yolk Sac Tumor ◽  
Appropriate Treatment ◽  
Curative Radiotherapy ◽  
Chief Complaints ◽  
Abdominal Mri ◽  
Malignant Germ Cell Tumor

Yolk sac tumor (YST) is a rare malignant germ cell tumor with no appropriate treatment strategy to date. However, patients are treated on a case-to-case basis as per various case reports that have been published. Here, we present a case of 27-year-old female patient who presented to us with chief complaints of severe abdominal pain associated with leucorrhea. She previously had a similar pain episode, which was then evaluated by a multidisciplinary team. She was diagnosed with YST. After that, she underwent 6 cycles of chemotherapy, but there was no improvement. Then the medical oncologist referred her to performed radiotherapy. Then, the radiation oncologist decided to give her curative radiotherapy of 3D-CRT. After completing her sessions, she felt better and clinically improving. After that, she was discharged and scheduled a follow-up visit for first evaluation. At her follow-up visit, she was feeling well, and we decided to have an abdominal MRI.

scholarly journals Early Consumption of Cannabinoids: From Adult Neurogenesis to Behavior

2021 ◽  
Vol 22 (14) ◽  
pp. 7450
Author(s):  
Citlalli Netzahualcoyotzi ◽  
Luis Miguel Rodríguez-Serrano ◽  
María Elena Chávez-Hernández ◽  
Mario Humberto Buenrostro-Jáuregui
Keyword(s):  
Young Adulthood ◽  
Adult Neurogenesis ◽  
Critical Period ◽  
Consumption Rate ◽  
Behavioral Outcomes ◽  
Endocannabinoid System ◽  
Illegal Drug ◽  
Adult Brain ◽  
As Stress

The endocannabinoid system (ECS) is a crucial modulatory system in which interest has been increasing, particularly regarding the regulation of behavior and neuroplasticity. The adolescent–young adulthood phase of development comprises a critical period in the maturation of the nervous system and the ECS. Neurogenesis occurs in discrete regions of the adult brain, and this process is linked to the modulation of some behaviors. Since marijuana (cannabis) is the most consumed illegal drug globally and the highest consumption rate is observed during adolescence, it is of particular importance to understand the effects of ECS modulation in these early stages of adulthood. Thus, in this article, we sought to summarize recent evidence demonstrating the role of the ECS and exogenous cannabinoid consumption in the adolescent–young adulthood period; elucidate the effects of exogenous cannabinoid consumption on adult neurogenesis; and describe some essential and adaptive behaviors, such as stress, anxiety, learning, and memory. The data summarized in this work highlight the relevance of maintaining balance in the endocannabinoid modulatory system in the early and adult stages of life. Any ECS disturbance may induce significant modifications in the genesis of new neurons and may consequently modify behavioral outcomes.

Experimental yolk sac dysfunction as a model for studying nutritional disturbances in the embryo during early organogenesis

Teratology ◽  
1990 ◽  
Vol 41 (4) ◽  
pp. 405-413 ◽  
Author(s):  
R. L. Brent ◽  
D. A. Beckman ◽  
M. Jensen ◽  
T. R. Koszalka
Keyword(s):  
Yolk Sac ◽  
Early Organogenesis ◽  
Nutritional Disturbances

The Role of the Coelomic Fluid in the Movements of Earthworms

1950 ◽  
Vol 27 (1) ◽  
pp. 110-122 ◽  
Author(s):  
G. E. NEWELL
Keyword(s):  
Short Review ◽  
The Body ◽  
Coelomic Fluid ◽  
Average Pressure ◽  
Normal Range ◽  
Tail Region ◽  
X Ray ◽  
Effective Barrier ◽  
Intrinsic Muscles

1. A short review is given of the coelom and of its morphological relations in the earthworm. 2. The arrangement of the intrinsic muscles in a typical septum is described. Four main sets of muscles are recognized: viz. radial muscles, circular muscles, oblique muscles, and the sphincter around the ventral foramen. 3. It is suggested that the function of the radial, circular and possibly of the oblique muscles is to control bulging of the septa, and so serve to localize differences in pressure in the coelomic fluid. Normally, in active worms, the sphincter of the ventral foramen is contracted and forms an effective barrier to the passage of fluid from one coelomic compartment to the next. This was verified experimentally and by X-ray photography. 4. A series of measurements of the pressure in the coelomic fluid in different regions of active worms was recorded by means of a capillary manometer and by the use of a spoon-gauge apparatus. Manometric measurements showed the average pressure in the anterior third of the body to be 16.0 cm. water and in the tail region to be 8.0 cm. water. The corresponding figures obtained with a spoon gauge were 13.5 and 8.5 cm. water. The pressure in narcotized worms is zero. 5. These results are discussed, and it is pointed out that the manometer readings suffer from the disadvantage of failing to show the rapid fluctuations in pressure which occur during wriggling movements of the worms. 6. It is calculated from these pressure readings that a worm can exert a forward thrust equivalent to forces of between 1.5 and 8.0 g. These figures agree well with those obtained by Gray & Lissman by the use of a special torsion balance. 7. The burrowing movements of earthworms are briefly described. 8. It is shown that the sphincters of the dorsal pores and of the nephridiopores do not normally allow of the escape of coelomic fluid, and will withstand a pressure well outside the normal range.

Turnover Intention Among the Navy People: The Role of Work Family Interference and Organizational Commitment

2021 ◽  
Vol 7 (2) ◽  
pp. 172
Author(s):  
Muhamad Zafran Whab ◽  
Raida Abu Bakar
Keyword(s):  
Organizational Commitment ◽  
Turnover Intention ◽  
Structural Equation ◽  
Negative Impact ◽  
High Capacity ◽  
Intention To Leave ◽  
Equation Modeling ◽  
Work Family ◽  
Navy Personnel

Human capital is a critical component of any organization's competitiveness. The absence of a high-capacity employee can have a negative impact on operational performance. The researcher examined the significance of organizational commitment as a mediator between work-family interference and turnover intention in the Royal Malaysian Navy. Data were collected from 400 navy personnel at the Lumut Naval Base in Perak, Malaysia, using structured questionnaires. Partial Least Squares-Structural Equation Modeling (PLS-SEM) was used to analyze the data. Organizational commitment serves as a mediator between work-family interference and turnover intention in the Royal Malaysian Navy. According to the findings of this study, organizational commitment mediated the relationship between work-family interference and turnover intention. Additionally, work-family interference is a significant predictor of intention to leave the RMN.

scholarly journals Extraocular Muscles Tension, Tonus, and Proprioception in Infantile Strabismus: Role of the Oculomotor System in the Pathogenesis of Infantile Strabismus—Review of the Literature

Scientifica ◽  
2016 ◽  
Vol 2016 ◽  
pp. 1-8 ◽  
Author(s):  
Costantino Schiavi
Keyword(s):  
Critical Period ◽  
Muscle Force ◽  
Sensory System ◽  
Oculomotor System ◽  
Extraocular Muscles ◽  
Review Of The Literature ◽  
Eye Muscle ◽  
System A ◽  
Concomitant Strabismus

The role played by the extraocular muscles (EOMs) in the etiology of concomitant infantile strabismus is still debated and it has not yet definitively established if the sensory anomalies in concomitant strabismus are a consequence or a primary cause of the deviation. The commonest theory supposes that most strabismus results from abnormal innervation of the EOMs, but the cause of this dysfunction and its origin, whether central or peripheral, are still unknown. The interaction between sensory factors and innervational factors, that is, esotonus, accommodation, convergence, divergence, and vestibular reflexes in visually immature infants with family predisposition, is suspected to create conditions that prevent binocular alignment from stabilizing and strengthening. Some role in the onset of fixation instability and infantile strabismus could be played by the feedback control of eye movements and by dysfunction of eye muscle proprioception during the critical period of development of the visual sensory system. A possible role in the onset, maintenance, or worsening of the deviation of abnormalities of muscle force which have their clinical equivalent in eye muscle overaction and underaction has been investigated under either isometric or isotonic conditions, and in essence no significant anomalies of muscle force have been found in concomitant strabismus.

Depletion of definitive gut endoderm in Sox17-null mutant mice

Development ◽  
2002 ◽  
Vol 129 (10) ◽  
pp. 2367-2379 ◽  
Author(s):  
Masami Kanai-Azuma ◽  
Yoshiakira Kanai ◽  
Jacqueline M. Gad ◽  
Youichi Tajima ◽  
Choji Taya ◽  
...  
Keyword(s):  
Es Cells ◽  
Definitive Endoderm ◽  
Lateral Region ◽  
Early Organogenesis ◽  
Stage Embryo ◽  
Endoderm Development ◽  
Null Mutant Mice ◽  
Gut Endoderm ◽  
Foregut Endoderm

In the mouse, the definitive endoderm is derived from the epiblast during gastrulation, and, at the early organogenesis stage, forms the primitive gut tube, which gives rise to the digestive tract, liver, pancreas and associated visceral organs. The transcription factors, Sox17 (a Sry-related HMG box factor) and its upstream factors, Mixer (homeobox factor) and Casanova (a novel Sox factor), have been shown to function as endoderm determinants in Xenopus and zebrafish, respectively. However, whether the mammalian orthologues of these genes are also involved with endoderm formation is not known. We show that Sox17–/– mutant embryos are deficient of gut endoderm. The earliest recognisable defect is the reduced occupancy by the definitive endoderm in the posterior and lateral region of the prospective mid- and hindgut of the headfold-stage embryo. The prospective foregut develops properly until the late neural plate stage. Thereafter, elevated levels of apoptosis lead to a reduction in the population of the definitive endoderm in the foregut. In addition, the mid- and hindgut tissues fail to expand. These are accompanied by the replacement of the definitive endoderm in the lateral region of the entire length of the embryonic gut by cells that resemble the visceral endoderm. In the chimeras, although Sox17-null ES cells can contribute unrestrictedly to ectodermal and mesodermal tissues, few of them could colonise the foregut endoderm and they are completely excluded from the mid- and hindgut endoderm. Our findings indicate an important role of Sox17 in endoderm development in the mouse, highlighting the idea that the molecular mechanism for endoderm formation is likely to be conserved among vertebrates.

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